Heating Basics – Gas Valve Systems - Direct Fired Heaters

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Heating Basics – Gas Valve SystemsUNI-LINE PRODUCT KNOWLEDGE 2010 Invensys. All Rights Reserved.The names, logos, and taglines identifying the products and services of Invensys are proprietary marks of Invensysor its subsidiaries. All third party trademarks and service marks are the proprietary marks of their respective owners.

Subjects We Will Cover In This Session Fuel and Pressure Characteristics Gas Valve Applications Gas Valve Actuator Types Gas Valve Characteristics Gas Valve Manufacturers Ignition Control System Ignition Manufacturers Flame Rectification Pilot Basics Thermocouple and Thermopile Basics Installation and Troubleshooting Tips Website Tools When You Have Questions Q&A2

Acronyms3BTU British Thermal UnitsLC Low CapacityLP Liquid PropaneMV Main ValveNAT Natural GasPD Pressure DropPV Pilot ValveSLC Snap-action Low CapacitymV milliVoltsWC Water Column

Fuel CharacteristicsNatural GasCharacteristicsLiquid Propane (LP)0.64Specific Gravity1.531000BTUs / Cubic Feet25007”WC – 10.5”WCService PressureRange11”WC – 14”WC1200º FIgnition Temperature950º F10/1Combustion24/1Air/Gas Ratio Natural gas is lighter than air and rises L.P. gas is heavier and puddles in the lowest area it can find4

Fuel Characteristics ofBritish Thermal Units Definition of BTU: The quantity of heat required to raise thetemperature of one pound of water one degree Fahrenheit Many gas appliances are rated depending on BTU output The more heat needed, the higher the BTU rating Residential gas water heaters (regardless of fuel) are rated between15,000 and 75,000 BTU Over 75,000 BTU is considered Commercial Water Heater Commercial Water Heaters rated between 75,000 and 750,000 BTU5

Pressure CharacteristicsPressure SideNatural GasLiquid PropaneInlet Pressure7” – 10” WC14” – 17” WC3” – 4” WC @ 1” PD10” – 11” WC @ 1” PDOutlet Pressure Excessive inlet pressure will not necessarily cause the gas valve to lock up– However, the valve will not regulate pressure correctly Gas line pressure from utilities vary seasonally with demand– During peak usage, inlet pressure can drop below the 7” WC Natural gas shown above High rise buildings may experience low pressure on upper floors– Especially during cold weather, many times a 2 psig system is used to compensate In some instances OEMs will specify higher outlet pressures– To obtain BTU rates beyond the capabilities of the gas valve at 1” pressure drop6

Central Heating ApplicationsFactory ModelBTU @ 1” PDMin - Max BTU CapacityStandingIntermittentDirectNat 300,00010,000 – 720,000999LP 485,00010,000 – 900,000999Nat 600,000200,000 – 800,000999LP 972,000300,000-1,150,000999Nat 150,00015,000 – 200,000999LP 240,00015,000 – 320,000999(Uni-Line Part)7000 STD(Uni-Line 700)7000 HC(Uni-Line 700)7200(Uni-Line 720)7

Space Heating And Hearth Applications8Factory ModelBTU @ 1” PDMin - Max BTU CapacityStandingIntermittentDirect7000 STDNat 300,00010,000 – 720,000999(Uni-Line 700)LP 485,00010,000 – 900,0009997200Nat 150,00015,000 – 200,000999(Uni-Line 720)LP 240,00015,000 – 320,0009992000Nat 125,00025,000 – 170,000899(Uni-Line 722)LP 200,00025,000 – 272,0008997500Nat 100,0006,700 – 160,000988(Uni-Line 722)LP 162,0006,700 – 226,0009887000 LCNat 40,0005,000 – 70,000988(Uni-Line 710)LP 65,0005,000 – 100,0009887000 STNat 100,00010,000 – 160,000988(Uni-Line 700)LP 162,00010,000 – 225,000988

Commercial Water Heating ApplicationsFactory ModelBTU @ 1” PDMin - Max BTU CapacityStandingIntermittentDirect7000 STDNat 300,00010,000 – 720,000999LP 485,00010,000 – 900,000999Nat 150,00015,000 – 200,000999LP 240,00015,000 – 320,000999Nat 125,00025,000 – 170,000899LP 200,00025,000 – 272,000899Nat 600,000200,000 – 800,000999LP 972,000300,000 – 1,150,000999(Uni-Line 700)7200(Uni-Line 720)2000(Uni-Line 722)7000 HC(Uni-Line 700)9

Commercial Cooking ApplicationsFactory ModelBTU @ 1” PDMin - Max BTU CapacityStandingIntermittentDirect7000 STDNat 300,00010,000 – 720,000999Temp Rating-40 to 175ºF(Uni-Line 700)LP 485,00010,000 – 900,0009997200Nat 150,00015,000 – 200,000999-40 to 175ºF(Uni-Line 720)LP 240,00015,000 – 320,0009992000Nat 125,00025,000 – 170,000899-40 to 175ºF(Uni-Line 722)LP 200,00025,000 – 272,0008997500Nat 100,0006,700 – 160,0009880 to 185ºF(Uni-Line 722)LP 162,00012,000 – 226,0009887000 LCNat 40,0005,000 – 70,000988-40 to 225ºF(Uni-Line 710)LP 65,0005,000 – 100,000988TS11 J &KNat 210,000NA98832 to 300ºF(Uni-Line 700)10LP 340,000NA988

Residential Water Heating ApplicationsFactory ModelBTU @ 1” PDMin - Max BTU CapacityStandingIntermittentDirect220RNat 86,00010,700 – 107,00098832 to 175ºF(Uni-Line 110)R103RVLP 100,0007,000 – 140,000988Nat NANA98832 to 175ºF(Uni-Line 110)2000LP 35,0003,500 – 35,000988Nat 125,00025,000 – 170,000899-40 to 175ºF(Uni-Line 722)R110RLP 200,00025,000 – 272,000899Nat 86,00010,700 – 107,00098832 to 175ºF(Uni-Line 110)LP 100,00011Temp Rating7,000 – 140,000988

Gas Valve Actuator Types Manual – Standing pilot valve manually turned ON and OFFfor each heating cycle. Millivolt – Wall thermostat actuated with manual gas cock,automatic pilot safety valve and a Millivolt operator. Theautomatic pilot safety is separate from gas cock and providesshutoff in case of pilot outage. Millivolt gas valves do notrequire external power source. 24 Volt, 120 Volt, and 240 Volt – Combines a manual mainand pilot gas valve, a separate automatic safety pilot valve,pilot filtration, and automatic electric valve. Hydraulic – Temperature is sensed by a capillary bulb. Thebulb in the return air stream is actuated open and close bythe hydraulic system.12

Millivolt Actuated Gas ValveWall ThermostatECO Limit(Energy Cut Off)Gas CockSafetyPilot Line 13OperatorPilot andThermopile

Robertshaw 700 & 710 Millivolt PTH1950 SeriesTwo-LeadThermopileOPERATORTH/TPTPTPTH1951 SeriesCoaxialThermopile

24 Volt Actuated – Standing Pilot SystemMost popular Uni-Line part is 710-402, Factory Part 7000-ERLCWall Thermostat24 VAC120 VACTransformerECO(Limit)High Limit NCFan Control NOGas CockFanMotorOperatorPilot andThermocouple15

Hydraulic Actuated – Standing Pilot System56F LO 1 2 3 4 5 6 7 8 HI 90FECO(Limit)Gas CockTemperatureControl KnobSensing BulbSafetyPilot andThermocouple16

Additional Gas Valve Characteristics Combination Gas Valves Open Valve Options– Standard Opening– Slow Opening– Step Opening– Two-stage Models Close Valve Options– Snap Action– Snap Throttle17

Combination Gas ValvesCombination valves include three components18 Regulation Safety valve Main valve actuated by thermostat or bulb

Additional Gas Valve CharacteristicsLEGENDOPENING CHARACTERISTICSRobertshaw Gas Valve Opening CharacteristicsSTANDARD OPENinstant full flow450,000400,000SLOW OPEN350,000S7A 0 - 5 sec. to full flowS7C 10 - 30 sec. to full flowSTEP OPENBTUS7B 5 - 10 sec. to full flow300,000Standard Open250,000Slow Open200,000Step Open150,000100,00050,000SO1 30% of full flowSO2 40% of full flow0015101520Time (s)SO3 50% of full flowSO4 60% of full flowSO5 70% of full flow1925303540

Additional Characteristics for Two-Stage20 Robertshaw two-stage gas valves use a two-stage, two-pressureregulator which responds to a two-stage controller (thermostat) Available in capacities from 29,000 to 960,000 BTU/Hr Piping sizes from 3/8 to 1 inch Can be used with either natural gas or liquid propane Two-stage has the ability to vary the gas pressure delivered to themain burner(s) through the use of a solenoid operated two-pressureregulator First stage actuator of the gas valve is energized When heat demand increases, the second stage regulator isenergized First stage setting is determined as a percentage of the full outputof the valve and is factory set Second stage pressure regulator setting is nominal 3.5” WC fornatural gas and 11” for LP

Snap-Action And Snap-ThrottleHydraulic Valves21

Gas Valve ManufacturersAttributesRobertshaw HoneywellWhite-RodgersDexenSITUS Based Engineering99988US Based Technical Services99888Space & Central99999Residential Water99988Hearth Products99899Pilot, Thermocouple and99989Ignition Controls22

Ignition Control Systems Standing Pilot Intermittent Pilot Ignition (IPI) Direct Spark Ignition (DSI) Hot Surface Ignition (HSI)23

Ignition SystemsFour Types of Ignition Systems Standing pilot – Pilot is manually ignited and stays on constantly. Whenthe thermostat calls for heat, and the pilot flame is making good contactwith the thermocouple, the gas valve allows gas to flow to main burneruntil the call for heat is satisfied. Intermittent pilot (also known as “spark to pilot”) – Pilot is ignited by aspark generated by an ignition module and electrode. When enough heatis generated in the thermocouple, the gas valve allows gas to the mainburner and is ignited by the pilot until the call for heat is satisfied. Direct spark – When the thermostat calls for heat, the main burner isignited by a direct spark or ceramic (glow bar) igniter. Eliminates the pilot,but requires flame sensor and more expensive ignition module. Hot Surface Ignition – Similar to Direct spark except it uses a “glowbar”or ceramic ignitor to heat up to ignition combustion temperature within17 or 34 seconds. There are Silicon Carbide (more fragile) and SiliconNitride versions available. Requires flame sensor.24

Acronyms25GRD GroundIGN IgnitionLP Liquid PropaneMV Main ValveNO Normally OpenNC Normally ClosedPV Pilot ValveV AC Voltage Alternating CurrentV DC Voltage Direct Current

Definitions Sensors - Senses the variable change in temperature and sends asignal to the controller. Transmitters - Interprets signal from sensor to display condition oftemperature variable. Transformer - An electromagnetic device that either raises orlowers the voltage of an alternating current electrical system. Voltage - The electrical potential pressure behind the flow ofelectricity, measured in terms of Volts. Current - The movement of an electrical charge through a circuit,measured in terms of Amps. Hertz - A unit of measurement for frequency in cycles per second ofa waveform. Relay - An electromechanical device that opens or closes contactswhen a current is passed through a coil.26

Gases Used In Applications Liquid Propane tends to hover at ground level Natural Gas rises, goes up the flue Manometer measures gas pressure– Inches of Water Column27

Ignition Control System1.2.3.4.5.28Thermostat calls for heatIgnition controller requests a spark to the electrode which ignites the gasControl uses flame rectification or sensor to identify if flame is presentIgnition controller sends signal to open gas valveWhen thermostat is satisfied, gas valve closes to shut off main burner gas

Feature List for Ignition Controls Approvals– CSA– UL Ease of Use– Local vs. Remote Sensing Some use Jumper Physical– 24V AC @ 50 / 60 Hz– Surface Mount Technology (SMT)– Conformal coating– Installable in NEMA-3R boxes– Quick connects or plugs– Diagnostic LEDs Application Timings– Trial Attempts (1, 3, infinite)– Ignition Timing (seconds)– Pre/post/inter-purge settings29 Safety– Hard Lockout– Auto-Restart Lockout Eliminates service calls

Pilot Ignition SystemFLAMESENSEUROBERTSHAW 780-745IGNValve OperatorTerminalsM C PTransformer24 VAC120 VACPVGRDTRPV/MVHighLimitNCTHMVFan Control NOIgnitionControlModulePilot Line 30Pilot andElectrode /SensorFanMotor

Intermittent Pilot Checkout Procedure Turn on main gas supply Turn on electrical powerU Turn on manual gas valveROBERTSHAW 780-745IGNFLAMESENSEValve OperatorTerminalsM C PTRPV/MVHighLimitNCTH Pilot Ignition - main burner ignition Turn manual gas valve off - burner & pilot go out Pilot ignites - main burner ignites31Fan Control NOIgnitionControlModule Air purged from gas line Sparking begins - turn manual valve on120 VACPVGRDMV Set thermostat to call for heat, spark beginsTransformer24 VACPilot Line Pilot andElectrode /SensorFanMotor

Intermittent Pilot Sequence of Operation Thermostat calls for heat Pilot gas flowsU Primary Valve (PV) opensROBERTSHAW780-745IGNFLAMESENSEValve OperatorTerminalsM C PTRPV/MVHighLimitNCTH Pilot flame impinges on electrode / sensor Main gas valve (MV) opens Main burner ignites Once thermostat satisfied, switch contacts open32Fan Control NOIgnitionControlModule Pilot gas ignites Main burner and pilot off120 VACGRDMV Sparking begins at burnerTransformer24 VACPVPilot Line Pilot andElectrode /SensorFanMotor

ROBERTSHAWHS780Hot Surface Ignition (HSI)THVALVEGNDTRGrounded WithMounting ScrewRS120IGNIGNNEUTIgnitionControlModule3324 VAC120 VACTransformerHighLimitNC

Hot Surface Ignition SystemGas ValveIgnition ControlHot Surface Ignitor34

Hot Surface Terminology Pre-Purge Cycle - Allows draft blower to purge the combustionchamber prior to start of equipment. Ignition Attempts - Number of times the system will attempt tolight the ignition if a flame is not detected. After last try, unit goesinto lockout. Valve Trial Time or Lockout Timing - Number of seconds the mainvalve is left open for ignition. If flame is not detected in a specifiedtime:1. The unit goes into lockout if it is a single try for ignition control or2. The unit sequences to next ignition attempt cycle if it is a multi-try. Sensor Type - The presence of a flame can be detected two ways:1. Local Sense, using a Hot Surface Ignitor to ignite the gas and detect thepresence of a flame.2. Remote Sense, using a sense rod that impinges into the main burnerflame. 35Ignitor Warm-Up Time - Time required for hot surface ignitor tocome up to operating temperature. An induced draft blower mayalso come on during this time period to purge the combustionchamber prior to the main valve opening.

Hot Surface Control Nomenclature36

Hot Surface Sequence of Operation Thermostat calls for heat, 24 Volts to ignition module Combustion blower & other relays are energized Non-purge modules - Ignition is powered in 1 second Pre-purge modules - Ignition powered in 17 or 34 seconds Ignitor heats to approximately 2500 degrees Fahrenheit After heat up, valve is activated allowing gas to flow to burner Ignitor shuts off at end of trial time and becomes the sensor If flame not sensed during trial time, the system shuts down If flame is sensed, system runs to satisfy thermostat demand37

Manufacturers Johnson Controls White-Rodgers Honeywell RAM Fenwal Robertshaw 38

Flame RectificationDC CURRENTAC CURRENTFlame Rod(Smaller)Flame Ground(Larger)PILOT / BURNERUsed On: IPI Intermittent Pilot Ignition DSI Direct Spark Ignition HSI Hot Surface IgnitionHow it Works: Rectifies AC Current into DC Requires flame to ground Proves pilot or burner ignitionGND39

Flame Rectification Pilot Ignitions40

Hot Surface Igniters Hot Surface Igniter Types– Silicon Carbide (fragile)– Silicon Nitride Robertshaw 41-400 Series– Silicon Carbide– Uni-Line Catalog Page 121 Robertshaw 41-400N Series– Silicon Nitride41

Ignitor Position42

Pilot Basics43

Pilot Parts Robertshaw 1820 Series with Left or Right flame pattern type Pilot Uni-Kits are with or without thermopile pre-mounted44

Thermocouple Basics“Hot” �� JunctionInsulatedCopperWireCopper SheathContactButtonUUUUUUULoad(Safety Magnet)45FittingNutContact Button

Thermocouple Parts The 1980 series offers easy installation into most pilot burners Uses Snap-Fit technology End of part number refers to various lengths:– 1980-012 is 12 inches– 1980-072 is 72 inches46

Thermocouple TestOpen circuit typically 20 to 25 MillivoltsHOTJUNCTION30 MVCOLDJUNCTION47CONTACTBUTTONMILLIVOLTMETER

Thermopile BasicsHotJunctionsColdJunctionsUUUUUULoad(Safety Magnet)UUUUUULoad(Gas Valve)481950 SeriesTwin LeadConnector

Thermopile Parts The 1950 series thermopiles have two lead wire connections andare primarily used in HVAC applications The 1951 coaxial series used on Commercial Cooking applicationsTwin lead wires49

Gas Valve Installation TipsDetermine: Natural Gas or Liquid Propane Inlet and Outlet Size BTU Requirement Ignition Method to be Used Outlet Pressure Setting Requirement Ambient Temperature Orientation of Gas Valve– Valves should not to be mounted upside down Actuator Type: 24 Volts, Millivolt, Hydraulic, Line Voltage Opening Speed of Gas Valve50

Troubleshooting Tips for Gas SystemsConditionFlame Too LargeNoisy FlameYellow Tip FlameFloating Flame51Possible CausePossible Cure1.Outlet pressure too high1.Outlet pressure too high2.Defective regulator2.Defective regulator3.Orifice too large3.Orifice too large1.Excessive primary air1. Adjust air shutter2.Noisy Pilot2. See Pilot Troubleshooting slide3.Burr in orifice3. Remove burr or replace orifice1.Too little primary air1.Adjust air shutter2.Clogged burner ports2.Clean burner ports3.Misaligned orifice3.Realign orifice and burner1.Blocked venting1.Inspect vent and clean2.Insufficient primary air2.Adjust air shutter

Troubleshooting Tips for Gas SystemsConditionPossible CausePossible CureDelayed Ignition1.2.3.4.Improper ignition locationPilot flame too smallBurner ports cloggedLow outlet pressure1.2.3.4.Reposition ignition sourceCheck orifice and cleanClean burner portsAdjust pressure regulatorFailure to Ignite1.2.3.4.Main gas “Off”Poor electrical connectionsDefective gas valveDefective thermostat1.2.3.4.Open manual valveCheck, clean, & tightenReplace with newReplace with newBurner won’t turn “Off”1. Poor thermostat location2. Defective gas valve3. Defective thermostat1. Relocate thermostat2. Replace with new3. Replace with newRapid Burn Cycles1. Clogged furnace filters2. Excess t-stat anticipation3. Poor thermostat location1. Clean or replace2. Adjust t-stat anticipator3. Relocate thermostat When all else fails Check supply is in the “ON” position52

Questions To Ask When SelectingIgnition Control Module1.What are you heating? What is OEM Factory Number?2.What is the supply voltage?3.What is the control voltage?4.Do you want to clear gas before, during, and/or after heating cycle?5.How many trials for ignition would you like?6.How many seconds between trials?7.What style of heating (direct spark, hot surface, or intermittent pilot)?8.Do you want remote or local sensing of flame (dual rod or single rod)?9.How do you want to handle lockout? How long?10. Do you want board enclosed or open?11. What type of connectors do you want?12. Do you need to change voltage levels, switch machines on or off, detect airpressure, replace parts, or need a kit?53

Troubleshooting TipsProblem # 1: Hot Surface Igniter Does Not Glow RedPossible Causes: No main power Faulty transformer Faulty thermostat- check call for heat Faulty limit switch Faulty blower interlock switch Faulty hot surface ignitor Faulty ignition control Remember to wait for purge time, 17 or 34 secondsTroubleshooting: With power on and thermostat at its highest position, check voltage between “TH” and“TR” on HS780 module– If 24 Volts is not present, check transformer output– If no 24 Volts present on secondary side, change transformer Check for 120 Volts at the igniter across “IGN” and “GND”– If voltage present, change ignitor– If no voltage present, change module54

Troubleshooting TipsProblem # 2: Igniter Glows Red but Main Burner Will Not LightPossible Causes: Improper igniter or sensor alignment Faulty ignition control Faulty gas valve High inlet gas pressures Polarity reversed No earth groundTroubleshooting: Check availability of gas at gas valve, check valve upstream is in ON position Check pressure is OK Check “GRD” and “PV/MV” by reversing wires– If reversed the gas valve will not open Check proper ignition position and properly grounded Check for 24 Volts at gas valve terminals “1” and “2” on a 7200 series, “TH” and “TR” on a 7000 series– If Yes, check wire re

two-stage gas valves use a two-stage, two-pressure regulator which responds to a two-stage controller (thermostat) Available in capacities from 29,000 to 960,000 BTU/Hr Piping sizes from 3/8 to 1 inch Can be used with either natural gas or liquid propane Two-stage has the ability to vary the gas pressure delivered to the

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